Although there are some good things to be said about this game every one seems to invite a "but..."
The levels are all very small. Hallways are narrow ceilings are low. The fact that the most common weapon mod increases range seems self mocking. The sniper rifle scope, a plus in most games, seems to be used to as a balancer in this game. You have to zoom to get the damage bonus, but since almost all your fights are in close quarters the zoom just makes the sniper rifle harder to use.
The physics engine is cool. I amused myself for a little while just shooting coffee cups off the shelf and throwing boxes around. But...
It never really seems to affect the game. In some cases it's just annoying. Like when you try to jump up on a crate only to watch it go flying across the room.
The no right answer, shades of grey, story line seems interesting at first. But...
Once you figure out that no matter what you do you are just helping the world's population to some degree of subjugation or destruction it just ends up being depressing. I also question the replay value, although opposing groups will give you opposing goals it's ultimately the same mission. You just choose whether to talk to a NPC or kill them at the end or which computer function to choose and the choice has no real affect on the next mission.
The action/RPG genre pioneered by Deus Ex 1 is still here, body mods and weapon mods are still fun. But...
Powerups are plentiful. You can easily have all of your biomods and weapon mods maxed out by midway through the game so unless you choose to change out functions the character growth in this "role playing game" doesn't last very long. In DX1 there were 3, 4, or 5 ways around every problem and how you approached it was governed by what skills/mods you had chosen, and what inventory you had brought along. In this game it seems like there are several ways around every problem and you have what you need to choose any of them. It's not role playing, it's just easy.
When I first played the demo, I was disappointed and wasn't even going to buy the game. Then I decided I was being unfair judging it against DX1 and maybe missing out. In the end this is one of those games that's just good enough to play to the end. Moments of brightness with lots of buts...